To the Editor.—We are writing to you in response to the Brief Report by Dr M. Witte and colleagues.1 We regret not getting a chance to address the issues raised in the report before publication and strongly object to the public assertion that implied some form of scientific impropriety. The customary scientific forum was used and our response to the critique by Witte et al was subjected to peer review by Science in 1992; however, the exchange was not considered worthy of publication by the reviewers for Science.Nevertheless, we made a concerted effort to address the concerns of Witte et al at the laboratory level. Dr C. Witte was contacted and we offered to have Dr Sakurada visit his laboratory and do experiments there, to have C. Witte visit our laboratory, or to send our cells and protocols to him. Our offer was flatly rejected. The same